This research is concerned with four aspects of the neuropsychology of ingestive behavior: the chemical controls of 1) thirst, and 2) sodium appetite, 3) the chemical controls of food satiety, and 4) the ontogeny of ingestive behavior. We are emphasizing the role of angiotensin in the mobilization of the thirst of extracellular depletions, and in the arousal of sodium appetite. Recently dicovered antidipsogens (prostaglandin E, Substance P) are being investigated for their selective competitive interaction with the dipsogenic action of angiotensin. And special use will be made of the opossum in which the subfornical organ, a demonstrated receptor site for angiotensin, is easly accessible for intimate study. Two approaches are being taken to the study of the chemical controls of food intake. First, denervation procedures are being employed to describe the mechanism of cholecystokinin-induced food satiety, with particular attention to the hepatic branches of the vagus. Second, physiological doses of catecholamines will be used to analyze the possible adrenergic mechanism for the arousal and suppression of the brain mechanisms for meal taking. The ontogeny of feeding and drinking is being studied in suckling and weanling rats with both appetitive and consumatory testing. The chronology of development of the separate physiological controls of each mode of ingestive behavior will be described and their assembly into adult feeding and drinking analyzed.